001// Copyright 2006, 2007, 2008, 2009 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.ioc.annotations;
016
017import org.apache.tapestry5.ioc.ServiceBinder;
018import org.apache.tapestry5.ioc.ServiceLifecycle;
019import org.apache.tapestry5.ioc.services.ServiceLifecycleSource;
020
021import java.lang.annotation.Documented;
022import static java.lang.annotation.ElementType.METHOD;
023import static java.lang.annotation.ElementType.TYPE;
024import java.lang.annotation.Retention;
025import static java.lang.annotation.RetentionPolicy.RUNTIME;
026import java.lang.annotation.Target;
027
028/**
029 * An optional annotation that may be placed on a service building method of a module, or on the implementation class
030 * (when using service binding). The annotation overrides the default scope for services (the default being a global
031 * singleton that is instantiated on demand) for an alternate lifecycle. Alternate lifecycles are typically used to bind
032 * a service implementation to a single thread or request. Modules may define new scopes. Each scope should have a
033 * corresponding {@link ServiceLifecycle} implementation. The linkage from scope name to service lifecycle occurs via a
034 * contribution to the {@link ServiceLifecycleSource} service configuration.
035 * <p/>
036 * The annotation may also be placed directly on a service implementation class, when using service binding (via
037 * the {@link ServiceBinder}).
038 *
039 * @see org.apache.tapestry5.ioc.ScopeConstants
040 */
041@Target(
042        {TYPE, METHOD})
043@Retention(RUNTIME)
044@Documented
045@UseWith({AnnotationUseContext.SERVICE, AnnotationUseContext.MODULE})
046public @interface Scope
047{
048    /**
049     * An identifier used to look up a non-default {@link ServiceLifecycle}.
050     */
051    String value();
052}